The present invention relates generally to production of, and injection into, subterranean wells and, in an embodiment described herein, more particularly provides a field development system and methods associated therewith.
To improve drainage of a formation, it has become quite common to drill one or more lateral wellbores extending outwardly from a parent wellbore and into the formation. An alternative is to drill numerous wellbores into the formation, but this generally requires additional production facilities for the additional wells. Such production facilities are very costly, so the choice is typically made to drill lateral wellbores where conditions warrant.
However, drilling lateral wellbores has its disadvantages as well. For example, a large amount of casing wear is usually experienced in drilling lateral wellbores. As another example, forming a pressure tight junction between the parent and lateral wellbores is a problem.
From the foregoing, it can be seen that it would be quite desirable to provide a field development system which enhances the drainage of a formation without requiring the drilling of lateral wellbores from a main producing wellbore, and without requiring numerous production facilities for numerous wellbores.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, a field development system is provided in which a main producing wellbore is placed in fluid communication with one or more additional wellbores extending within a formation. Associated methods are also provided.
In broad terms, a method is provided which includes the steps of drilling a second wellbore to intersect a fracture extending outward from a first wellbore and flowing fluid between the first and second wellbores through the fracture. Both the first and second wellbores may intersect a formation into which the fracture extends, in which case the second wellbore effectively extends the drainage of the formation by the first wellbore, without the need of drilling a lateral wellbore from the first wellbore. Alternatively, the second wellbore may intersect a formation which is not intersected by the first wellbore, in which case the second wellbore provides a conduit by which the formation may be drained by the first wellbore.
The second wellbore may be equipped with a fluid property sensor, which may be in communication with a receiver in the first wellbore for transmission of fluid property indications to the surface. The sensor may be utilized to detect when water enters the second wellbore. Several of the second wellbores with sensors therein may be arranged in an array about the first wellbore, in which case an advancing sweep of water may be detected in two or more dimensions.
The advantages of the present invention may also be used in water flood or steam injection applications. For example, an injection well may be placed in fluid communication with additional wellbores drilled in a formation via fractures which extend outward from the injection well and intersect the additional wellbores.
In another aspect of the present invention, drainage wellbores which are drilled to intersect fractures extending outward from a main wellbore are plugged between the formation and the earth""s surface. Thus, no additional production facilities are utilized to produce fluids from the drainage wellbores.
In yet another aspect of the present invention, the drainage wellbores may be drilled as lateral wellbores extending outward from a parent wellbore. The drainage wellbores may be drilled in more than one formation also intersected by the main production wellbore. Alternatively, the main production wellbore may not intersect one or more of the formations in which the drainage wellbores are drilled.
In still another aspect of the present invention, flow between a drainage wellbore and the main production wellbore may be prevented by releasing a flow blocking substance in the drainage wellbore. This may be useful, for example, to prevent water encroachment from the drainage wellbore to the main production wellbore. The flow blocking substance may be released by flowing a particular fluid, such as acid, from the main production wellbore into the drainage wellbore via a fracture.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings.